Since in [1]} it is shown that no initial transmission phase
is needed, here the details of the computation is given for \(i \ge 1\) . In what follows, we use \(\sigma _{X_{\left( k \right)i} }^2\) , \(\sigma _{Y_i }^2\)  to denote the variances of \({X_{\left( k \right)i} }\)  and \(Y_i\) , respectively, and \(\sigma _{X_{\left( k \right)i} Y_i }\)  for the covariance of \(X_{\left( k \right)i}\)  and \(Y_i\) .
